I'm going to have to take issue with this view of 'signature' architects. No doubt its very true in the case of Frank Gehry's Guggenheim Museum in Bilbao, Spain. That project was really known for how it brought tourism to the area and really pumped up the local economy, just by being such a cool building. BUT... Thats one great commission from a great client with a huge budget. After doing 'the big one' the high profile architects get asked to do all sorts of smaller jobs all over the country and world, and each time the little clients think they're going to be the next Bilbao, but it just ain't so. We have a Maya Lin ampitheater, but there is little doubt in my mind that this is one of her 'lesser works' or perhaps a 'secondary design' of hers. If you were to rank her artistic achievements... Rosa Parks Circle isn't going to be anywhere near the top of the list. I don't see crowds of tourists crowding onto Monroe to see Maya's design. So GR bought a Maya Lyn, but if I didn't know it, I might have assumed it was done by a city engineer.
These lesser "Me Too! I want a building by 'so and so' too!" projects often keep the designers office of interns busy, but generally don't receive a huge amount of "The Masters" time. There are some international projects whose situation is ripe for a really great star designer, but most are probably better off with local talent. You'd be amazed at how cool of building some designers in GR could come up with given the leeway, challenge, and the budget to do so.